U.S. patent number 7,040,403 [Application Number 10/649,029] was granted by the patent office on 2006-05-09 for methods for controlling migration of particulates in a subterranean formation.
This patent grant is currently assigned to Halliburton Energy Services, Inc.. Invention is credited to Johnny A. Barton, Philip D. Nguyen, Thomas E. Rush, Jimmie D. Weaver.
United States Patent |
7,040,403 |
Nguyen , et al. |
May 9, 2006 |
Methods for controlling migration of particulates in a subterranean
formation
Abstract
The present invention relates to methods for controlling the
migration of particulates, such as proppant and formation sands,
from subterranean formations using solutions of tackifying
materials. One embodiment of the present invention provides a
method of treating a subterranean formation comprising the steps of
placing a tackifying composition into the subterranean formation
and then placing an after-flush fluid into the subterranean
formation.
Inventors: |
Nguyen; Philip D. (Duncan,
OK), Rush; Thomas E. (Richmond, TX), Weaver; Jimmie
D. (Duncan, OK), Barton; Johnny A. (Marlow, OK) |
Assignee: |
Halliburton Energy Services,
Inc. (Duncan, OK)
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Family
ID: |
34216847 |
Appl.
No.: |
10/649,029 |
Filed: |
August 27, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050049151 A1 |
Mar 3, 2005 |
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Current U.S.
Class: |
166/281; 166/294;
166/295 |
Current CPC
Class: |
C09K
8/506 (20130101); C09K 8/508 (20130101); C09K
8/575 (20130101); C09K 8/5751 (20130101); C09K
8/62 (20130101); C09K 8/80 (20130101) |
Current International
Class: |
E21B
33/138 (20060101); E21B 43/267 (20060101) |
Field of
Search: |
;166/281,294,295
;523/131 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 879 935 |
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Nov 1998 |
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EP |
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1132569 |
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Dec 2001 |
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EP |
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Other References
Foreign Search Report and Opinion (PCT Appl. No. GB2004/002943),
Nov. 19, 2004. cited by other .
Attia, Yosry, et al, Adsorption Thermodynamics of a Hydrophobic
Polymeric Flocculant on Hydrophobic Colloidal Coal Particles, 1991,
American Chemical Society, Langmuir, 7, pp. 2203-2207. cited by
other.
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Primary Examiner: Suchfield; George
Attorney, Agent or Firm: Kent; Robert A. Baker Botts
Claims
What is claimed is:
1. A method of treating a subterranean formation comprising the
steps of: (a) placing a tackifying composition into the
subterranean formation so as to form a coating on one or more
particulates present in the subterranean formation, wherein the one
or more particulates were present in the subterranean formation
prior to the placement of the tackifying composition therein; and,
(b) placing an after-flush fluid into the subterranean
formation.
2. The method of claim 1 further comprising, before step (a), the
step of: placing a pre-flush fluid into the subterranean
formation.
3. The method of claim 2 wherein the pre-flush fluid comprises an
aqueous liquid selected from the group consisting of fresh water,
salt water, brine, seawater, and combinations thereof.
4. The method of claim 2 wherein the pre-flush fluid further
comprises a surfactant.
5. The method of claim 4 wherein the surfactant is selected from
the group consisting of an ethoxylated nonyl phenol phosphate.
6. The method of claim 2 where in the pre-flush fluid is placed
into the subterranean formation at a matrix flow rate. ester, a
cationic surfactant, a non-ionic surfactant, an alkyl phosphonate
surfactant, and combinations thereof.
7. The method of claim 1 wherein the tackifying composition
comprises a tackifier.
8. The method of claim 7 wherein the tackifier is selected from the
group consisting of a polyamide, a polyester, a polycarbonate,
polycarbamate, a natural resin and combinations thereof.
9. The method of claim 1 wherein the tackifying composition further
comprises a solvent.
10. The method of claim 9 wherein the solvent is selected from the
group consisting of butylglycidyl ether, dipropylene glycol methyl
ether, butyl bottom alcohol, dipropylene glycol dimethyl ether,
dimethyl formamide, diethyleneglycol methyl ether, ethyleneglycol
butyl ether, methanol, butyl alcohol, isopropyl alcohol,
diethyleneglycol butyl ether, propylene carbonate, d'limonene,
2-butoxy ethanol, butyl acetate, furfuryl acetate, butyl lactate,
dimethyl sulfoxide, dimethyl formamide, a fatty acid methyl ester,
and combinations thereof.
11. The method of claim 1 wherein the viscosity of the tackifying
composition is less than about 100 cP.
12. The method of claim 1 wherein the percent active tackifier in
the tackifying composition is from about 1% to about 10%.
13. The method of claim 1 wherein the after-flush fluid comprises
an aqueous liquid selected from the group consisting of fresh
water, salt water, brine, seawater, and combinations thereof.
14. The method of claim 1 wherein the after-flush fluid further
comprises a surfactant.
15. The method of claim 14 wherein the surfactant is selected from
the group consisting of an ethoxylated nonyl phenol phosphate
ester, a cationic surfactant, a non-ionic surfactant, an alkyl
phosphonate surfactant, and combinations thereof.
16. The method of claim 1 where in the tackifying composition is
placed into the subterranean formation at a matrix flow rate.
17. The method of claim 1 where in the after-flush fluid is placed
into the subterranean formation at a matrix flow rate.
18. The method of claim 1 wherein the one or more particulates are
selected from the group consisting of formation sand, proppant, and
combinations thereof.
19. The method of claim 1 wherein the coating formed on the one or
more particulates is a non-hardening coating.
20. The method of claim 1 wherein the coating covers 100% of the
outer surface of the one or more particulates.
21. A method of controlling fines migration in a subterranean
formation comprising the steps of: (a) placing a tackifying
composition into the subterranean formation so as to form a coating
on one or more particulates present in the subterranean formation,
wherein the one or more particulates were present in the
subterranean formation prior to the placement of the tackifying
composition therein; and, (b) placing an after-flush fluid into the
subterranean formation.
22. The method of claim 21 further comprising, before step (a), the
step of: placing a pre-flush fluid into the subterranean
formation.
23. The method of claim 22 wherein the pre-flush fluid comprises an
aqueous liquid selected from the group consisting of fresh water,
salt water, brine, seawater, and combinations thereof.
24. The method of claim 22 wherein the pre-flush fluid further
comprises a surfactant.
25. The method of claim 24 wherein the surfactant is selected from
the group consisting of an ethoxylated nonyl phenol phosphate
ester, a cationic surfactant, a non-ionic surfactant, an alkyl
phosphonate surfactant, and combinations thereof.
26. The method of claim 22 where in the pre-flush fluid is placed
into the subterranean formation at a matrix flow rate.
27. The method of claim 21 wherein the tackifying composition
comprises a tackifier.
28. The method of claim 27 wherein the tackifier is selected from
the group consisting of a polyamide, a polyester, a polycarbonate,
polycarbamate, a natural resin and combinations thereof.
29. The method of claim 21 wherein the tackifying composition
further comprises a solvent.
30. The method of claim 29 wherein the solvent is selected from the
group consisting of butylglycidyl ether, dipropylene glycol methyl
ether, butyl bottom alcohol, dipropylene glycol dimethyl ether,
dimethyl formamide, diethyleneglycol methyl ether, ethyleneglycol
butyl ether, methanol, butyl alcohol, isopropyl alcohol,
diethyleneglycol butyl ether, propylene carbonate, d'limonene,
2-butoxy ethanol, butyl acetate, furfuryl acetate, butyl lactate,
dimethyl sulfoxide, dimethyl formamide, a fatty acid methyl ester,
and combinations thereof.
31. The method of claim 21 wherein the viscosity of the tackifying
composition is less than about 100 cP.
32. The method of claim 21 wherein the percent active tackifier in
the tackifying composition is from about 1% to about 10%.
33. The method of claim 21 wherein the after-flush fluid comprises
an aqueous liquid selected from the group consisting of fresh
water, salt water, brine, seawater, and combinations thereof.
34. The method of claim 21 wherein the after-flush fluid further
comprises a surfactant.
35. The method of claim 34 wherein the surfactant is selected from
the group consisting of an ethoxylated nonyl phenol phosphate
ester, a cationic surfactant, a non-ionic surfactant, an alkyl
phosphonate surfactant, and combinations thereof.
36. The method of claim 21 where in the tackifying composition is
placed into the subterranean formation at a matrix flow rate.
37. The method of claim 21 where in the after-flush fluid is placed
into the subterranean formation at a matrix flow rate.
38. The method of claim 21 wherein the one or more particulates are
selected from the group consisting of formation sand, proppant, and
combinations thereof.
39. The method of claim 21 wherein the coating formed on the one or
more particulates is a non-hardening coating.
40. The method of claim 21 wherein the coating covers 100% of the
outer surface of the one or more particulates.
Description
FIELD OF THE INVENTION
The present invention relates to methods for controlling the
migration of particulates, such as proppant and formation sands, in
subterranean formations using solutions of tackifying
materials.
DESCRIPTION OF THE PRIOR ART
Hydrocarbon wells are often located in subterranean zones that
contain unconsolidated particulates that may migrate within the
subterranean formation with the oil, gas, water, and/or other
fluids produced by the wells. The presence of particulates, such as
formation sand, in produced fluids is disadvantageous and
undesirable in that the particulates may abrade pumping and other
producing equipment and reduce the fluid production capabilities of
the producing zones. Unconsolidated subterranean zones include
those that contain loose particulates and those wherein the bonded
particulates have insufficient bond strength to withstand the
forces produced by the production of fluids through the zones.
One method of controlling particulates in unconsolidated formations
involves placing a filtration bed containing gravel near the well
bore in order to present a physical barrier to the transport of
unconsolidated formation fines with the production of hydrocarbons.
Typically, such so-called "gravel packing operations" involve the
pumping and placement of a quantity of a desired particulate into
the unconsolidated formation in an area adjacent to a well bore.
One common type of gravel packing operation involves placing a
gravel pack screen in the well bore and packing the surrounding
annulus between the screen and the well bore with gravel of a
specific size designed to prevent the passage of formation sand.
The gravel pack screen is generally a filter assembly used to
retain the gravel placed during gravel pack operation. A wide range
of sizes and screen configurations are available to suit the
characteristics of the gravel pack sand used. Similarly, a wide
range of sizes of gravel is available to suit the characteristics
of the unconsolidated or poorly consolidated particulates in the
subterranean formation. The resulting structure presents a barrier
to migrating sand from the formation while still permitting fluid
flow. When installing the gravel pack, the gravel is carried to the
formation in the form of a slurry by mixing the gravel with a
viscose transport fluid. Once the gravel is placed in the well
bore, the viscosity of the transport fluid is reduced, and it is
returned to the surface. Some gravel packing operations, commonly
known as "high-rate water packing" operations, the transport fluid
viscosity is somewhat lowered and yet the gravel remains in
suspension because the treatment occurs at a substantially higher
velocity. Gravel packs act, inter alia, to stabilize the formation
while causing minimal impairment to well productivity. The gravel,
inter alia, acts to prevent the particulates from occluding the
screen or migrating with the produced fluids, and the screen, inter
alia, acts to prevent the gravel from entering the production
tubing. Such packs may be time consuming and expensive to
install.
Another method used to control particulates in unconsolidated
formations involves consolidating unconsolidated subterranean
producing zones into hard, permeable masses by applying a resin
followed by a spacer fluid and then a catalyst. Such resin
application may be problematic when, for example, an insufficient
amount of spacer fluid is used between the application of the resin
and the application of the external catalyst. The resin may come
into contact with the external catalyst in the well bore itself
rather than in the unconsolidated subterranean producing zone. When
resin is contacted with an external catalyst an exothermic reaction
occurs that may result in rapid polymerization, potentially
damaging the formation by plugging the pore channels, halting
pumping when the well bore is plugged with solid material, or
resulting in a down hole explosion as a result of the heat of
polymerization. Also, using these conventional processes to treat
long intervals of unconsolidated regions is not practical due to
the difficulty in determining if the entire interval has been
successfully treated with both the resin and the external
catalyst.
In addition to the unconsolidated formation sands often found in
subterranean formations, particulate materials are often introduced
into subterranean zones in conjunction with conductivity enhancing
operations and sand control operations. Conductivity enhancing and
sand control operations may be performed as individual treatments,
or may be combined where desired.
SUMMARY OF THE INVENTION
The present invention relates to methods for controlling the
migration of particulates, such as proppant and formation sands,
from subterranean formations using solutions of tackifying
materials.
One embodiment of the present invention provides a method of
treating a subterranean formation comprising the steps of placing a
tackifying composition into the subterranean formation and then
placing an after-flush fluid into the subterranean formation.
Another embodiment of the present invention provides a method of
controlling fines migration in a subterranean formation comprising
the steps of placing a tackifying composition into the subterranean
formation and then placing an after-flush fluid into the
subterranean formation.
Other and further objects, features and advantages of the present
invention will be readily apparent to those skilled in the art upon
a reading of the description of preferred embodiments which
follows.
DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention relates to methods for controlling the
migration of particulates, such as proppant and formation sands,
from subterranean formations using solutions of tackifying
materials.
One embodiment of the present invention describes a method of
controlling particulates in a subterranean formation comprising the
steps placing successively into a subterranean zone an optional
pre-flush fluid, a low-viscosity tackifying composition, and an
after-flush fluid.
When used, suitable pre-flush fluids comprise an aqueous liquid
and, optionally, a surfactant. The aqueous liquid used may be fresh
water, salt water (e.g., water containing one or more salts
dissolved therein), brine, seawater, or any other aqueous liquid
that does not adversely react with the other components used in
accordance with this invention or with the subterranean formation.
In some embodiments of the present invention, it may be desirable
to add a surfactant to the pre-flush fluid. The surfactant may act,
inter alia, to prepare the formation particulates to accept and
adhere the tackifying material.
Any surfactant compatible with the later-used low-viscosity
non-curable tackifying composition and capable of facilitating the
coating of the tackifying composition on the subterranean particles
and aiding the tackifying composition in flowing to the contact
points between adjacent particulates in the formation may be
optionally used in the present invention. Such surfactants include,
but are not limited to, ethoxylated nonyl phenol phosphate esters,
mixtures of one or more cationic surfactants, one or more non-ionic
surfactants, and an alkyl phosphonate surfactant. Suitable mixtures
of one or more cationic and nonionic surfactants are described in
U.S. Pat. No. 6,311,773 issued to Todd et al. on Nov. 6, 2001, the
disclosure of which is incorporated herein by reference. A C.sub.12
C.sub.22 alkyl phosphonate surfactant is preferred. The surfactant
or surfactants used are included in the aqueous liquid in an amount
sufficient to prepare the subterranean formation to receive a
treatment of low-viscosity resin by wetting the particulates in the
formation so that the resin can attach to those particulates. In
some embodiments of the present invention, the aqueous surfactant
fluid comprises surfactant in an amount ranging from about 0.1% to
about 15% by weight of the aqueous liquid.
Tackifying compositions suitable for use in the methods of the
present invention exhibit a sticky character and, thus, impart a
degree of consolidation to particulates but they do not cure or
harden over time. Compounds suitable for use as a tackifier in the
tackifying compositions of the present invention comprise
substantially any compound which, when in liquid form or in a
solvent solution, will form a non-hardening coating upon a
particulate. A particularly preferred group of tackifiers comprise
polyamides which are liquids or in solution at the temperature of
the subterranean formation such that the polyamides are, by
themselves, non-hardening when present on the particulates
introduced into the subterranean formation. A particularly
preferred product is a condensation reaction product comprised of
commercially available polyacids and a polyamine. Such commercial
products include compounds such as mixtures of C.sub.36 dibasic
acids containing some trimer and higher oligomers and also small
amounts of monomer acids that are reacted with polyamines. Other
polyacids include trimer acids, synthetic acids produced from fatty
acids, maleic anhydride and acrylic acid and the like. Such acid
compounds are commercially available from companies such as Witco
Corporation, Union Camp, Chemtall, and Emery Industries. The
reaction products are available from, for example, Champion
Technologies, Inc. and Witco Corporation. Additional compounds
which may be used as tackifying compounds include liquids and
solutions of, for example, polyesters, polycarbonates and
polycarbamates, natural resins such as shellac and the like.
Suitable tackifying compounds are described in U.S. Pat. No.
5,853,048 issued to Weaver, et al. and U.S. Pat. No. 5,833,000
issued to Weaver, et al., the disclosures of which are herein
incorporated by reference.
In order for the tackifying composition of the present invention to
achieve a low enough viscosity to be suitable for use in the
present invention, a solvent may be needed. The methods of the
present invention call for the viscosity of the tackifying
composition to be less than about 100 cP, preferably less than
about 50 cP, and still more preferably less than about 10 cP. The
concentration of tackifier in the tackifying composition may be
quantified by considering the percent of active tackifier as
compared to the percentage of active tackifier before any solvent
is added. In some embodiments of the present invention, the
tackifying composition is from about 0.1% to about 50% active,
preferably from about 1% to about 10% active.
It is within the ability of one skilled in the art, with the
benefit of this disclosure, to determine whether a solvent is
needed to achieve a viscosity suitable to the subterranean
conditions and, if so, how much. Any solvent that is compatible
with the tackifying agent and achieves the desired viscosity
effects is suitable for use in the present invention. The solvents
that can be used in the present invention preferably include those
having high flash points (most preferably above about 125.degree.
F.). Examples of solvents suitable for use in the present invention
include, but are not limited to, butylglycidyl ether, dipropylene
glycol methyl ether, butyl bottom alcohol, dipropylene glycol
dimethyl ether, diethyleneglycol methyl ether, ethyleneglycol butyl
ether, methanol, butyl alcohol, isopropyl alcohol, diethyleneglycol
butyl ether, propylene carbonate, d'limonene, 2-butoxy ethanol,
butyl acetate, furfuryl acetate, butyl lactate, dimethyl sulfoxide,
dimethyl formamide, fatty acid methyl esters, and combinations
thereof.
In the methods of the present invention, the after-flush fluid
acts, inter alia, to remove the solvent used to the control the
viscosity of the tackifying composition. Suitable after-flush
fluids comprise an aqueous liquid and, optionally, a surfactant.
The aqueous liquid used may be fresh water, salt water (e.g., water
containing one or more salts dissolved therein), brine, seawater,
or any other aqueous liquid that does not adversely react with the
other components used in accordance with this invention or with the
subterranean formation. In some embodiments of the present
invention, it may be desirable to add a surfactant to the
after-flush fluid. The surfactant may act, inter alia, to prepare
the formation particulates to accept and adhere the tackifying
material. Any surfactant compatible with the low-viscosity
non-curable tackifying composition and capable of aiding the
after-flush fluid to flow to the contact points between adjacent
particulates in the formation may be used in the present invention.
Such surfactants include, but are not limited to those listed above
in connection with the pre-flush fluid.
Following the placement of the after-flush, what remains is a
relatively concentrated film or layer of consolidating tackifying
composition on the proppant or formation sand. That layer of
tackifying composition acts, inter alia, to prolong the production
rates of the well as high as possible by controlling the movement
of subterranean particulates and keeping them from plugging
productive pore spaces and channels. The ability of the tackifying
composition to form a thin layer on the formation particulates
allows the methods of the present invention to be useful even in
situations where the pore spaces are relatively small, such as
following an acidizing treatment, or before or after hydraulic
fracturing, frac packing, water fracturing, and gravel packing.
The pre-flush fluid, tackifying composition, and after-flush fluid
are preferably introduced to the subterranean formation at a matrix
flow rate. That is, the fluids are added at such a rate that they
are able to penetrate the formation without substantially effecting
the structure of the formation sands or proppant matrixes they
encounter.
To facilitate a better understanding of the present invention, the
following examples of some of the preferred embodiments are given.
In no way should such examples be read to limit the scope of the
invention.
EXAMPLES
Example 1
Tackifying compositions were made comprising 75% to 78% dipropylene
glycol methyl ether by weight of the composition, 20% butyl bottom
alcohol by weight of the composition, and tackifier fluid. The
amount of tackifier fluid ranged from 2% to 5% by weight of the
composition.
A first series of tests was preformed on a simulated formation sand
mixture comprising 88% 70/170-mesh natural sand, 10% silica fines,
and 2% smectite, all by weight of the total sand mixture. The sand
mixture was packed into a Hassler sleeve, pre-flushed with a
solution of 5% NH.sub.4Cl brine, and the initial permeability of
the packed sand mixture was determined. Next, the tackifying
composition was introduced to the packed sand mixture, followed by
an after-flush fluid of 5% NH.sub.4Cl brine. The flow rates of the
pre-flush fluid, tackifying composition, and after-flush fluid were
all kept to between 1 mL/minute and 10 mL/minute to maintain a
matrix flow rate. The permeability of the packed sand mixture was
again determined after the after-flush treatment was complete. In
all of the tests, the permeability of the packed sand mixture after
the after-flush treatment was found to be either the same as or
higher than the initial permeability of the packed sand
mixture.
Example 2
A second series of tests was run using the tackifying compositions
described above and involved visualization microscopy through
micro-cells. The microcells were prepared by packing and sealing in
place between two microscopy slides 16/30-mesh re-sieved sand and
200-mesh and smaller formation sand. Inlet and outlet ports were
connected to the packed slide using 6-gauge needles. A syringe pump
was used to inject 5 mL of a pre-flush solution of 5% NH.sub.4Cl
brine, followed by 2 mL of the tackifying composition described
above, followed by 5 mL of an after-flush solution of 5% NH.sub.4Cl
brine. The injection rates of the pre-flush fluid, tackifying
composition, and after-flush fluid were all kept to between 1
mL/minute and 2 mL/minute to maintain a matrix flow rate. A control
was also developed wherein no tackifying composition or after-flush
fluid were injected.
To simulate production, brine was injected into the outlet port of
the packed slide. When production was simulated on the control
slide, the fines quickly dispersed, migrated, and invaded the pore
spaces of the 16/30-mesh sand. When production was simulated on the
packed slides that had been treated with a tackifying composition
and an after-flush fluid, no migration of fines was noted even when
the "production" flow rate was surged and paused repeatedly. The
migration of the fines was equally well controlled with a
tackifying composition comprising 2% active tackifier and one
comprising 5% active tackifier.
Therefore, the present invention is well adapted to carry out the
objects and attain the ends and advantages mentioned as well as
those that are inherent therein. While numerous changes may be made
by those skilled in the art, such changes are encompassed within
the spirit and scope of this invention as defined by the appended
claims.
* * * * *